Since I necro’d this post I figured I’d post the solution I found here for the next guy.
First, I found a post about modifying engine code to fix the issue. I hope this means that in future versions of Unreal this may be fixed. Here’s the link to that post if you’re interested in that route: Camera Lag doesn't work with `AutoCalculateOrthoPlanes`?
I was not interested in working from a source engine for my project due to the level of simplicity I’m trying to keep, so I found a different workaround.
I’m using a top down ortho cam panning deal to smoothly pan my camera around the scene. To get the desired effect, I simply made a blueprint actor as a “camera anchor” that I then move based on my click inputs on my controller. The camera anchor is an empty actor with a spring arm with the lag setup how I like. I’m then attaching my camera pawn to the spring arm so the camera can sit at the root of the pawn still, but the pawn is moving with the lag. Works like a charm.